PNNL

The Water Cycle and Climate Extremes Modeling (WACCEM) Scientific Focus Area advances predictive understanding of water cycle variability and change through foundational research using models, observations, and novel numerical experiments and analysis methods. Our objective is to advance understanding and modeling of water cycle processes as influenced by large-scale atmospheric circulation, mesoscale convection, and surface–atmosphere interactions.

Our research on large-scale circulation will unravel the mechanisms behind the summer circulation in the midlatitudes and the boreal summer intraseasonal oscillation in the tropics, as well as future changes in these phenomena that impact regional extremes.

On mesoscale convection, we will address major gaps in understanding mesoscale convective organization over the tropical oceans and characterize extreme mesoscale convective system precipitation over global land areas.

On surface–atmosphere interactions, we will focus on subseasonal-to-interannual predictability that may be gained from integrated considerations of the two-way interactions between intraseasonal signals and surface–atmosphere interactions over land and ocean for extreme events and their synchronization.

The Energy Exascale Earth System Model (E3SM), our primary modeling tool, will be enhanced and used in combination with a model hierarchy including large eddy simulations and machine learning models for hypothesis testing and causal discovery. WACCEM’s focus on: (a) extreme events, which have increasingly threatened water and energy security; (b) organized convection, with significant implications for hydrological cycle; and (c) contribution of surface–atmosphere interactions to predictability of extremes will provide foundational knowledge and capabilities to support DOE’s energy, environment, and national security goals.